I don't have a K 1 but based on my research and the excellent reviews here on the forum
perhaps this info might be of help to the OP and others
" Pentax K-1 Review
Available Lenses
The Pentax K-1 is compatible with every Pentax K-mount lens ever made without the need for an adapter, and with little or no restrictions in terms of functionality: this includes over 204 genuine full-frame lenses in addition to thousands of third-party offerings. Furthermore, you can adapt M42, M37, 645, and 6x7 lenses. Refer to our lens compatibility guide for further details, or seek advice in the lens forum. . . .
Read more at:
Pentax K-1 Review - Available Lenses | PentaxForums.com Reviews
Full-Frame Compatible DA lenses
Ricoh Imaging has confirmed that the Pentax DA★ 200mm F2.8, DA★ 300mm F4, and DA 560mm F5.6 lenses support the full-frame image circle. To this end, the K-1 includes correction profiles for these lenses in both full-frame and crop modes. These lenses were originally marketed as APS-C only.
Read more at:
Pentax K-1 Review - Available Lenses | PentaxForums.com Reviews
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Pentax K-1 Lens Compatibility Guide
Everything you need to know about lenses for the K-1
By PF Staff in Articles and Tips on Feb 20, 2016
Read more at:
Pentax K-1 Lens Compatibility Guide - Articles and Tips | PentaxForums.com
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DA lenses on Full Frame: Test Shots thread
Posted By: falconeye, 07-07-08, 15:50 (Offline)
Hi everybody,
I would like to open up a thread dedicated to one topic:
DA lens on Full Frame: a sticky test shots thread.
This thread shall be dedicated to test shots of a DA lens mounted to a full frame body (e.g., a film camera body). By test shot, I mean shots dedicated to evaluate the performance. Shots of ordinary subjects aren't suitable to this task, normally, and should not be posted. So, these are the rules:
Read more at:
DA lenses on Full Frame: Test Shots thread - Page 34 - PentaxForums.com
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http://www.mosphotos.com/PentaxLensCompatibility.html